1. Field of the Invention
This invention relates to carburettors for air and liquid fuel under pressure for internal combustion engines where a partial vacuum is created in the intake manifold attached to the engine, the vacuum thus created drawing the air/fuel mixture into the engine. The fuel and air under pressure in a nozzle creates a spray effect inside a chamber, the vacuum created by the engine acting on the fuel/air mixture in the chamber to vaporise same, additional air being let into the chamber to create the correct fuel/air ratio for complete combustion in the engine.
2. Description of the Prior Art
In known carburettors the air passes through a passage in the carburettor called the choke tube. The air flow has to be of a velocity sufficient to create a spray effect on the liquid in the jet; thus in order to keep the speed of the air flow as high as possible there has to be a limitation on the size of the choke tube. As less air is required at low revolutions of the engine, the air flow is restricted by a valve or plate in the air passage, the air flow passing through the choke tube is thus attenuated and its action on the fluid in the jet is lessened causing a poor spray effect. The air/fuel mixture will thus contain large droplets or globules of fuel that pass through the intake manifold into the engine, producing inefficient combustion.
As a liquid or a spray will tend to vaporize more easily in a vacuum the air passing through a normal carburettor in the region of the jet will lessen the vacuum effect in this area, thus the vaporizing acting of the vacuum on the fuel spray will be lowered.
The carburettor embodied in this invention utilises the improved spray effect of a spray nozzle described and claimed in the specification of my U.S. Pat. No. 4,116,382, issued on Sept. 26, 1978. Whereas preferred embodiments of the said specification disclose the production of a pressurized spray of water and air, the liquid in the case of the carburettor described in the present specification is a combustible fuel and the spray-mist entering an enclosed chamber is acted on by the vacuum created by the engine, the liquid in spray form being vaporized, the mixture of air and vaporized fuel being drawn into the engine to produce combustion. This invention provides other benefits which will be described below.